Zhau et al [Electroanal. 18 (2006)830] have simultaneously determined tyrosine and tryptophan at unmodified boron—doped diamond electrode. Reference is made to several chemically modified electrodes viz. multiwalled carbon nanotube (MWCNT) modified GCE [Microchim. Acta 151 (2005) 47], L-Serine polymer film modified GCE [Colloids & Surfaces B. Biointerfaces 50 (2006)147], and MWCNT-4-aminobenzene sulphonic acid modified GCE [Colloids & surfaces B. Biointerfaces 61 (2008) 176] which are described for tyrosine sensing. Tang et al [Talanta 80 (2010)2182] have reported construction of electrospun carbon nanofibre modified carbon paste electrode for simultaneous voltammetric sensing of L-tyrosine, L-tryptophan and L-cysteine. Reference may be made to Overoxidized polypyrrole modified carbon paste electrode for sensing of tryptophan [Anal. Sci. 18 (2002) 417].
In 2008 Liu et al reported an improved voltammetric response of L-tyrosine employing MWCNT-ionic liquid composite coated GCE in presence of cupric ion [Electroanal. 20 (2008)2148]. Again, two other reports on adsorptive voltammetric determination of tyrosine [Fresnius J. Anal. Chem 351 (1995)689] and enrofloxacin using hanging mercury drop electrode are also described employing copper(II) during voltammetric sensing.
Yet another reference may be made to multifunctional and multispectral biosensor device for polynucleotides, polypeptides & peptides [Vo-Dinh U.S. Pat. No. 6,743,581; 2004], selector molecule adsorbed or immobilized poysiloxane coated biosensor [Levon et. al Inter. Pat. No. WO 059507; 2005], chemical sensor featuring dual sensing (surface plasmon resonance & fluorescence detection) motif for sensing pinacolyl methyl phosphonate [Booksh et al, U.S. Pat. No. 0,031,292; 2007]. References may be made to a method for a conducting polymer coated sensing electrode for detecting polar toxic species [Venkatasetty, U.S. Pat. No. 4,662,996; 1987], protein adsorbed shapable electroconductive polymer film[Wolfgang et al, Euro. Pat. No. 0658906; 1994], sensor comprising a substrate containing nanoparticles of a conducting polymer, polyaniline[Morrin et al, Int. Pub. No. WO2007/119229; 2007], a method of determining analyte concentrations by utilizing analyte sensors that employ conducting organic polymers covalently functionalized with an enzyme, antigen or an ion specific binding site and employed in a diagnostic device to selectively assay a liquid medium [Albarella et al, Euro. Pub. No. 0314009; 1988]. The drawbacks of the above mentioned matrices for sensing amino acids are the lack of selectivity, poor stability, need to incorporate selective recognition moieties in the conducting polymer or other matrices like MWCNT, L-serine etc. Another reference may be made to a few molecularly imprinted electrosynthesized polymer modified electrodes viz. copolymerization of o-phenylenediamine and resorcinol for sensing of dopamine [J. Solid state chem. 14 (2010)1909], polypyrrole for ascorbic acid sensing [Sensors 8 (2008)5792], overoxidised polypyrrole for sulphamethaxozole sensing [Sensors 8 (2008)8463] and molecularly imprinted poly (3,4-ethylene dioxy-thiophene-co-thiophene acetic acid] employing platinum electrode for atrazine sensing [Anal. Chim Acta 649 (2009)236].
Yet another reference may be made to imprinted polymer based quartz crystal microbalance sensors using polymerizable chiral derivatives of cysteine and homocysteine for peptide templates like Oxytocin, Vasopressin, Angiotensin II, Bradykinin and 15-mer peptide [Tai et al U.S. Pat. No. 0,226,503; 2008], dual MIP/QCM sensor for polychloroaromatic contaminants [Penelle, U.S. Pat. No. 0,166,581; 2004], analysis kit for sensing dopamine & ochratoxin A [Perollier et al U.S. Pat. No. 0,105,076; 2010], affinity electrode modified with synthetic polymers for the detection of phenols, morphines and phenoxy acid herbicides [Kroger & Mosbach GB Pat. No. 2337332; 1999], process for fabrication of ISFET based potentiometric sensor coated with molecular imprint of cholesterol [Vanaja et al, U.S. Pat. No. 0,147,683; 2010], molecularly imprinted sensor device for detecting drugs like gamma hydroxy butyrate (GHB), ketamine and cortisol [Murray et al U.S. Pat. No. 0,197,297; 2009], bionic nanosensing film of electrochemical transducer [Zhou et al Chinese Pat. No. CN 101196486; 2008], method for producing macromolecule identifying polymer [Minoura et al, U.S. Pat. No. 7,741,421; 2010], peptide imprinted polymers with integrated emission sites (PIPIES) [Bright, U.S. Pat. No. 7,598,087; 2009], method of combining surface molecular imprinting (SMI) with the production of self-assembled monolayers (SAM) on gold coated chip surfaces for the detection of cancer biomarkers [Levon et al U.S. Pat. No. 0,318,788; 2009] and a method of molecular imprinting for recognition in aqueous media [Naraghi et al U.S. Pat. No. 0,099,301; 2009]. MIPs are formulated as an adhesive in an in-vitro diagnostic device to release template molecules to capture target molecules [Meathrel et al U.S. Pat. No. 0,068,820; 2010].
The above mentioned references pertaining to molecular imprinted substrates are superior to other sensing platforms due to excellent predetermined selectivity, ruggedness, can afford absence of specific reagents for selective molecular recognition as the cavities inside the polymer matrices itself are tailor made for the analyte under consideration rendering a label free sensing. However, the present embodiment holds an extra advantage which synchronizes the high selectivity of imprinted polymers with the excellent conducting properties of conducting polymers viz. polypyrrole which improves the signal transduction considerably. Also, the enhanced catalytic properties rendered by metal oxide makes the present embodiment an excellent sensing platform with good sensitivities and remarkable selectivity.